In the drilling and completion industry, the formation of boreholes for the purpose of production or injection of fluid is common. The boreholes are used for exploration or extraction of natural resources such as hydrocarbons, oil, gas, water, and CO2 sequestration. Various downhole tools function therein by actuating specific components while being operated in the borehole. One method of activating a downhole tool is the application of fluid pressure to hydraulic components included in the tool.
One such downhole tool is a pressure actuated sleeve used in a cementing assembly that is responsive to tubing pressure to open a port. When the pressure is built up in the tubing to a certain point, access is provided to a piston on the sleeve that is referenced to a low pressure or atmospheric chamber by breaking a rupture disc. The sleeve can then move to open the port or ports for annulus access. Other types of downhole tools also use pressure operated sleeves that respond to tubing pressure with an associated piston that is open on one side to tubing pressure and on the other side to annulus pressure.
In addition to using a burst disk, downhole tools are held in a deactivated state through the use of either a shear pin, shear screw, shear ring, or seal friction. These methods have limited repeatability, most within +/−5-10 of applied pressure, and therefore do not afford the operation of a well with more accurate pressure actuation windows, posing a problem in wells that have limited casing pressure ratings. Additionally, these prior devices for actuating tools are not changeable by the end user, but will only operate at an “as delivered” pressure, which is not always within acceptable ranges.
Therefore, the art would be receptive to a device and method for actuating tools downhole that provides for more actuation accuracy, while allowing for tuneability to ensure that the device will operate within an acceptable pressure range.